There is a wide range of MTB helmets on the market and it can be quite confusing at times. However, you can divide mountain bikes helmets into 4 categories to help you choose the best MTB helmet for you.
Cross Country Helmets
Cross country helmets are quite comparable to road helmets. They are fitted with large vents to keep your head cool. However, they are made of tougher material and are therefore a little heavier than road helmets.
Trail riding helmets have more coverage on the back and temples than the cross country ones. They usually have a front peak and can be fitted with a goggle retention system. These helmets are heavier than the cross country ones and while they still are well ventilated, the vents tend to be smaller.
Dirt Jumping Helmets
Dirt jump helmets have less vents than the two types of mountain biking helmets mentioned above to ensure maximum protection. They are very strong and covers as much of your face as possible. They are designed to take the multiple impacts you might endure on a dirt track.
Full Face Mountain Bike Helmets
The full face helmets are used by gravity and enduro cyclists looking to get the maximum protection possible. Their shell is usually made of EPP, an elastic shell allowing for multiple impacts. They come with limited vents and a chin bar. They can easily be combined with goggles or sunglasses.